3 years ago

Domain Structures of Ni and NiFe (Oxy)Hydroxide Oxygen-Evolution Catalysts from X-ray Pair Distribution Function Analysis

Domain Structures of Ni and NiFe (Oxy)Hydroxide Oxygen-Evolution Catalysts from X-ray Pair Distribution Function Analysis
Shannon W. Boettcher, Forrest A. L. Laskowski, David M. Tiede, Gihan Kwon, Adam S. Batchellor
Ni–Fe (oxy)hydroxides, Ni(1–z)FezOxHy, are among the fastest-known water oxidation catalysts in alkaline media on a per-cation basis. At current densities relevant for electrolysis (e.g., >0.5 A/cm–2), mass and electron transport through catalyst films with high mass loading are critical and depend substantially on the extended and intermediate catalyst architecture. Here we use X-ray pair distribution function (PDF) analysis to determine the intermediate nanostructures of electrodeposited Ni(1–z)FezOxHy films. We report the effects of electrodeposition technique (pulsed versus continuous), electrochemical cycling, and Fe content on the structure of the catalyst film. The PDF patterns for Ni(1–z)FezOxHy films are best simulated by model structures consisting of brucite-like β-Ni(OH)2 fragments 1 to 3 layers in thickness. Only the oxidation state of the film significantly affects the intralayer scattering behavior (i.e., metal–oxygen bond distance). The interlayer interactions, however, are affected by Fe content and deposition conditions. The domain size of many of the systems are similar, extending to ∼5 nm, which are best modeled by sheets containing upward of ∼250 metal cations. Smaller domains were found for films deposited through a larger number of electrochemical cathodic current pulses. Films can be cycled between as-deposited, oxidized, and reduced states, with minimal loss of intrasheet coherence, indicating a degree of structural stability. We estimate heterogeneity in the domain structures by modeling the PDF data to linear combinations of oxyhydroxide fragments with different sizes and numbers of layers.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b10306

DOI: 10.1021/acs.jpcc.7b10306

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.